In general the treatment is not limited to recovery fluid of mechanical processing, but is also carried out to recover residual liquids of other types of processing. The treatment of said waters is made necessary by a series of reasons.
A first reason is of the ecological type, and requires that the muds that form in said waters be separated to allow recycling or else discharge thereof into the environment.
A second reason is of the economic type, since a substantial amount of processing chips are contained in the muds, and when the worked piece is made from a valuable material this implies a need to recover the chips.
A third reason is the perfect and complete separation of the material filtered from the treated liquid.
A last but not least reason is the need to improve the safety of the workplace.
With particular reference to the recovery liquids of mechanical processing, they consist of water, water/oil emulsions or even just oil.
The recovery of the liquids is particularly important in fine processing, for example lapping, of metal surfaces coated with precious and valuable materials like for example nickel.
Plants suitable for treating residual water of mechanical processing are known, comprising filtering means, in series or in parallel, consisting of a toroidal filtering cartridge arranged in a cylindrical box that is divided by the cartridge into two concentric parts, the central one of which can also communicate with the outside through an opening foreseen on the bottom of the box for the evacuation of mud.
The liquid to be filtered is generally fed inside (to the centre) of the cartridge, crosses it and is evacuated outside of the box.
The solid material contained in the liquid remains lodged inside the cartridge where it forms a layer that must be periodically removed, since as it increases in thickness it progressively clogs up the cartridge.
In known plants the removal is carried out through a periodic washing in equicurrent, in other words spraying the layer of mud through nozzles and collecting the material that detaches through suitable means.
The periodic cleaning system of the cartridge takes place at fairly long time intervals, which depend upon the amount of mud contained in the liquid, and the size of the particles of which it is made up.
The washing action is generally controlled by detecting the pressure inside the cartridge, which increases as the clogging increases.
It has been noted that known plants have some difficulty in operating well when the residual liquids of fine processing are treated, like the aforementioned lapping. In these cases, indeed, the size of the chip particles is in the order of between 0.1 and 7.0 microns, and the mud not only tends to clog up the filtering cartridge very quickly, but the washing operation carried out in the conventional way is not sufficient to restore the characteristics of the cartridge.
The clogging of the cartridge, indeed, does not depend exclusively upon the thickness of the layer of mud that forms on the filtering surface, but also upon the partial insertion of the particles to be separated in the pores of the filtering surface.
The purpose of the present invention is to provide a method and plant for managing the filters in systems for treating the leftover liquids of mechanical processing that does not have the aforementioned drawbacks.
A further purpose of the present invention is that of making a separating apparatus for muds from mechanical processing that is able to work continuously without requiring that the machines for mechanical processing connected to it be stopped.
Yet another purpose of the present invention is that of making a separating apparatus for muds from mechanical processing that is compact and also easy to connect to filtering apparatuses, decanting tanks and machines for mechanical processing that are already known and operating.
Another technical task of the present invention is that of providing a double suction submerged pump structure suitable for recycling the liquids in the above mentioned filtering plant
The further purpose of the present invention is that of making a double suction submerged pump structure with vertical axis in which the axial thrusts on the drive shaft are balanced and which has a pump structure that can be applied particularly to tanks for collecting liquids containing muds from mechanical processing.
Another important purpose of the present invention is that of making a pneumatic valve suitable for the above mentioned plant, that wears down less from the passage of metallic muds from mechanical processing with respect to known valves, and that can easily be managed without electrical or electronic management and control means.
In the technical tasks outlined above, an important purpose of the present invention is that of making a separating and recovery device of liquids from muds processed by the above mentioned plants that is able to make the solid part recovered from such muds disposable.